7,569 research outputs found
Universal Properties of Galactic Rotation Curves and a First Principles Derivation of the Tully-Fisher Relation
In a recent paper McGaugh, Lelli, and Schombert showed that in an empirical
plot of the observed centripetal accelerations in spiral galaxies against those
predicted by the Newtonian gravity of the luminous matter in those galaxies the
data points occupied a remarkably narrow band. While one could summarize the
mean properties of the band by drawing a single mean curve through it, by
fitting the band with the illustrative conformal gravity theory with fits that
fill out the width of the band we show here that the width of the band is just
as physically significant. We show that at very low luminous Newtonian
accelerations the plot can become independent of the luminous Newtonian
contribution altogether, but still be non-trivial due to the contribution of
matter outside of the galaxies (viz. the rest of the visible universe). We
present a new empirical plot of the difference between the observed centripetal
accelerations and the luminous Newtonian expectations as a function of distance
from the centers of galaxies, and show that at distances greater than 10 kpc
the plot also occupies a remarkably narrow band, one even close to constant.
Using the conformal gravity theory we provide a first principles derivation of
the empirical Tully-Fisher relation.Comment: 6 pages, 15 figures. The paper is a comment on S. S. McGaugh, F.
Lelli, and J. M. Schombert, Phys. Rev. Lett. 117, 201101 (2016). Updated to
include a first principles derivation of the Tully-Fisher relation using the
conformal gravity theory. Submitted to Physics Letters
Liquid crystal anchoring transitions on aligning substrates processed by plasma beam
We observe a sequence of the anchoring transitions in nematic liquid crystals
(NLC) sandwiched between the hydrophobic polyimide substrates treated with the
plasma beam. There is a pronounced continuous transition from homeotropic to
low tilted (nearly planar) alignment with the easy axis parallel to the
incidence plane of the plasma beam (the zenithal transition) that takes place
as the exposure dose increases. In NLC with positive dielectric anisotropy, a
further increase in the exposure dose results in in-plane reorientation of the
easy axis by 90 degrees (the azimuthal transition). This transition occurs
through the two-fold degenerated alignment characteristic for the second order
anchoring transitions. In contrast to critical behavior of anchoring, the
contact angle of NLC and water on the treated substrates monotonically declines
with the exposure dose. It follows that the surface concentration of
hydrophobic chains decreases continuously. The anchoring transitions under
consideration are qualitatively interpreted by using a simple phenomenological
model of competing easy axes which is studied by analyzing anchoring diagrams
of the generalized polar and non-polar anchoring models.Comment: revtex4, 18 pages, 10 figure
Alternative gravity rotation curves for the Little Things Survey
Galactic rotation curves have proven to be the testing ground for dark matter
bounds in spiral galaxies of all morphologies. Dwarf galaxies serve as an
increasingly interesting case of rotation curve dynamics due to their typically
rising rotation curve as opposed to the flattening curve of large spirals.
These galaxies usually vary in galactic structure and mostly terminate at small
radial distances. This, coupled with the fact that Cold Dark Matter theories
struggle with the universality of galactic rotation curves, allow for exclusive
features of alternative gravitational models to be analyzed. Recently, the
THINGS (The HI Nearby Galactic Survey) has been extended to include a sample of
25 dwarf galaxies now known as the LITTLE THINGS Survey. Here, we present a
thorough application of alternative gravitational models to the LITTLE THINGS
survey, specifically focusing on conformal gravity and Modified Newtonian
Dynamics. An analysis and discussion of the results of the fitting procedure of
the two alternative gravitational models are explored, as well as the resulting
rotation curve predictions of each. Further, we show how these two alternative
gravitational models account for the recently observed universal trends in
centripetal accelerations in spiral galaxies. We posit here that both conformal
gravity and MOND can provide an accurate description of the galactic dynamics
without the need for dark matter.Comment: 13 Pages, 7 Figures, Accepted in Astrophysical Journa
MITOCHONDRIAL MASS, DISTRIBUTION AND ACTIVITY DURING SEA URCHIN OOGENESIS
The sea urchin egg is a favourite model for studies of the molecular biology and physiology of fertilization and early development, yet we know sparingly little of its oocytes and of mitochondria behaviour during oogenesis.
The process of oogenesis in most echinoderms is asynchronous so each ovary lobe has hundreds of oocytes at all stages of development. At the beginning of oogenesis, the oocyte is about 10 \ub5m in diameter. During the vitellogenic phase of oogenesis, the oocyte accumulate yolk proteins and grow to ten times their original size to 80 to 100 \ub5m in sea urchins. The oocyte, arrested at the prophase of the first meiotic division, is apparent with its large nucleus, the germinal vesicle (GV), containing a prominent nucleolus. Echinoid (such as sea urchin) and Holothurian oocytes complete meiotic maturation prior to fertilization, distinct from other echinoderms and almost all others animals. As maturation progresses, it occurs the GV breaks down (GVBD). These eggs may then be stored for weeks to months within the female before they are spawned, and the proportion of eggs in the ovary increases from early to late season, as the numbers of oocytes decline [1].
Mitochondria, generally known as the powerhouses of eukaryotic cells, play a primary role in cellular energetic metabolism, homeostasis and death. These organelles, with their multicopy genome maternally inherited, are directly involved at several levels in the reproductive process since their functional status influences the quality of oocytes and contributes to the process of fertilization and embryonic development.
It has been demonstrated that the number of maternal mitochondria is sufficient to support development until late stages without new synthesis of mitochondrial DNA or production of new organelles [2]. During embryogenesis mitochondrial mass does not change, whereas mitochondrial respiration increases [3]. The behaviour of these organelles during oogenesis remains at moment unclear.
In the present paper we studied, by Confocal Laser Scanning Microscopy tecnologies (CLSM), the mass and distribution, the activity and the DNA content of sea urchin Paracentrotus lividus mitochondria during oogenesis, by in vivo incubating oocytes of different size with cell-permeant probes specific for mitochondria and for DNA and by immunodetection of hsp60 chaperonine, a well known mitochondrial marker.
In particular the oocytes were grouped in six classes: < 10, 20/30, 40/50, 60/70, 80/90 \ub5m, and 90 \ub5m ovulated egg, on the base of diameters. Microscopic observations were performed capturing 2 \ub5m thick layers of oocytes. Of the several thousands oocytes we observed, 20 for each different oogenesis stage were analyzed and processed. In order to interpret results and to draw unequivocal conclusions, we measured by IMAGE J software analysis the intensity values of fluorescent signals, as suggested in Agnello et al 2008 [4].
The mitochondria of oocytes with a diameter between 20 and 70 \ub5m, appeared to give rise to clusters that disappear in that of 80 \ub5m. In the oocytes between 60 and 90 \ub5m the red fluorescence seems to be more evident around the germinal vesicle (the merge tends to red), suggesting an increasing oxidative phosphorylation activity.
In the ovulated eggs, red and green fluorescence are uniformly distributed suggesting that mitochondria are dispersed in the cytoplasm. In addition the merge of green and red colours shows that the whole mitochondrial population is consuming oxygen at the same level (the resulting colours tends to yellow), figure 1.
In order to calculate the total mitochondrial mass and activity we integrated the values of pixel intensities for all captured sections and used the arithmetic means to draw a statistical analysis. Results suggest a parallel rise of mitochondrial mass and activity, suggesting that the amount and activity of organelles change remarkably during oogenesis.
Figure 1. shows the distribution of hsp60 protein, detected by immunofluorescence analysis (A), the mitochondrial and genomic DNA, after in vivo incubation with PicoGreen probe (B) and the merge of green and red fluorescence signal, respectively due to mitochondrial mass and activity, after in vivo incubation with Mitotraker Green and Orange (C). The size of the oocytes reported is 80 \ub5m.
Results suggest that mitochondria are actively duplicating and that mitochondrial DNA is replicating during the different oogenesis phases. It is noteworthy that around the germinal vesicle, especially in the larger oocytes, next to the germinal vesicle breakdown, the organelles are more active in oxygen consumption, probably due to the major energetic needing in this key moment of gametogenesis.
[1] Wessel G.M., Voronina E., and Brooks J.M. (2004) Obtaining and handling echinoderm oocytes. In \u201cMethods in Cell Biology\u201d, Elsevier. Vol.74, Chapter 5, pp. 87-114.
[2] Matsumoto L., Kasamatsu H., Pik\ub4o L. and Vinograd J. (1974) Mitochondrial DNA replication in sea urchin oocytes. J. Cell Biol. 63: 146\u2013159.
[3] Morici G., Agnello M., Spagnolo F., Roccheri M.C., Di Liegro C.M. and Rinaldi A.M. (2007) Confocal microscopy study of the distribution, content and activity of mitochondria during Paracentrotus lividus development. Journal of Microscopy. 228: 165-173.
[4] Agnello M., Morici G., Rinaldi A.M. (2008) A method for measuring mitochondrial mass and activity . Cytotechnology. 56: 145-149.
Maria Carmela Roccheri: Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche. Universit\ue0 degli Studi di Palermo, Viale delle Scienze Ed.16, Palermo, Italy; tel: 09123897414;
e-mail: [email protected]
SELECTION OF THE BEST OOCYTES FOR INTRACYTOPLASMICSPERM INJECTION (ICSI) USING APOPTOTIC ANALYSIS OF CUMULUS CELLS
Introduction: We studied the apoptosis rate of the cumulus cells of individual cumulus-oocyte
complex (COC), to verify a relationship with clinical outcomes, in terms of pregnancy and
implantation rates. Usually oocytes are selected using morphological criteria. We tried to verify
if cumulus cell apoptotic rate could be used as molecular criteria in selecting oocytes with higher
implantation potentiality (1;2).
Materials and Methods: The study design consisted in two different trials: in the first, we
investigated apoptosis rate in cumulus cells of the three selected oocytes, to be fertilized by
intracytoplasmic sperm injection (ICSI); in a second trial, average apoptosis rate of the cumulus
cells coming from the three selected oocytes to be fertilized by ICSI and the pooled remaining
oocytes were compared, when more than 5 COCs were aspirated. In a first trial we included 22
consecutive couples undergoing ICSI cycles, 20 in a second one, for a total of 42 patients. We
selected the three oocytes for (ICSI) on the basis of the morphological appearance of the
cumulus, according to Veek’s criteria. The cumulus cells of each COC were submitted to
apoptotic assays (3). The patients were classified, on the basis of pregnancy success, in A Group
(pregnant patients) and B Group (patients with negative βhCG).
Results: Both trials showed that apoptosis in the cumulus cells was remarkably lower in the A
Group if compared with B Group. The apoptosis rate in the selected COCs was similar to pooled
COCs for each patient, confirming that apoptosis rate in cumulus cells is characteristic for
patient. Out of 22 patients involved in the first trial, 8 were pregnant (36.3% A Group) and 14
were not pregnant (B Group). In the second trial 4 of a total of 20 patients were pregnant (20%).
In the first trial a total of 58 metaphase II oocytes and 56 in the second trial were studied. In the
second trial 38 oocytes where pooled to compare apoptosis rate with the three selected oocytes
pools. In the first trial the incidence of DNA fragmentation, evaluated by TUNEL assay (fig. 1),
of the cumulus cells from individual treated oocytes, was lower in A Group than in B Group
(6.7% ranging between 2.2–13.3 vs 13.19% ranging between 6.2–34.9 respectively, p<0.05). To
confirm if DNA fragmentation was related to apoptosis process, we performed caspase-3
immunoassay in the same cells (fig. 2). Data showed a lower capase-3 activity in cumulus cells
of pregnant than in those of non-pregnant patients (5.2% ranging between 1.2–8.6 vs 11.8%
ranging between 5.6–14.8, p<0.05). It is noteworthy to underline that pregnant patients usually
exhibited, at least, one COC with a DNA fragmentation rate (TUNEL) less than 10% and
caspase-3 activity rate less than 7%. Four (A Group) of 20 patients involved in the second trial
were pregnant but two aborted at 8–9 weeks. The low number of pregnant patients did not allow
us to have a powerful statistical analysis of apoptotic rate in cumulus cells, but it seems evident
that a higher apoptotic rate in cumulus cells is associated to the pregnancy failure (B Group) and
in aborted patients of A Group, ranging from 10 to 60.3%.
Conclusion: The data seem to demonstrate that apoptosis may be a marker for the selection of
the best oocytes to be submitted to ICSI treatment. All pregnant patients showed a lower
apoptosis rate in cumulus cells if compared with patients with pregnancy failure.
86° CONGRESSO NAZIONALE SIBS - PALERMO 24-25 OTTOBRE 2013
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References
1. Ruvolo G, Bosco L, Pane A, Morici G, Cittadini E, Roccheri MC. Lower apoptosis rate in
human cumulus cells after administration of recombinant luteinizing hormone to women
undergoing ovarian stimulation for in vitro fertilization procedures. Fertil Steril. 2007 Mar;
87(3):542-6. Epub 2006 Nov 27.
2. Host E, Gabrielsen A, Lindenberg S, Smidt-Jensen S 2002 Apoptosis in human cumulus cells
in relation to zona pellucida thickness variation, maturation stage, and cleavage of the
corresponding oocyte after intracytoplasmic sperm injection. Fertility and Sterility 77, 511-515.
3. Bosco L, Ruvolo G, Morici G, Manno M, Cittadini E, Roccheri MC. Apoptosis in human
unfertilized oocytes after intracytoplasmic sperm injection. Fertil Steril. 2005 Nov; 84(5):1417-
23.
FIGURE 1. Apoptosis evaluation using TUNEL assay in human cumulus cells. (A1, A2, A3) A
group; (B1, B2, B3) B group; (C1, C2, C3) positive control for TUNEL assay. (A1, B1, C1)
fragmented DNA; (A2, B2, C3) propidium iodide staining; (A3, B3, C3) merge. Scale bar = 15
μm.
FIGURE 2. Apoptosis evaluation using Cleaved caspase 3 immunofluorescence in situ assay in
human cumulus cells. (A1, A2, A3) A group; (B1, B2, B3) B group; (A1, B1) Cleaved caspase 3;
(A2, B2) propidium iodide staining; (A3, B3) merge. Scale bar = 15 μm
APOPTOTIC ANALYSIS OF CUMULUS CELLS FOR THE SELECTION OF COMPETENT OOCYTES TO BE FERTILIZED BY INTRACYTOPLASMIC SPERM INJECTION (ICSI)
Oocyte quality is one of the main factors for the success of in vitro fertilization protocols.
Apoptosis is known to affect oocyte quality and may impair subsequent embryonic development and
implantation. The aim of this study was to investigate the apoptosis rate of single and pooled
cumulus cells of cumulus cell\u2013oocyte complexes (COCs), as markers of oocyte quality, prior to
intracytoplasmatic sperm injection (ICSI).We investigated the apoptosis rate by TUNEL assay
(DNA fragmentation) and caspase-3 immunoassay of single and pooled cumulus cells of COCs.
The results showed that DNA fragmentation in cumulus cells was remarkably lower in patients who
achieved a pregnancy than in those who did not. Cumulus cell apoptosis rate could be a marker for
the selection of the best oocytes to be fertilized by intracytoplasmatic sperm injection
Resisted adduction in hip neutral is a superior provocation test to assess adductor longus pain:an experimental pain study
The criterion of long-standing groin pain diagnoses in athletes usually relies on palpation and clinical tests. An experimental pain model was developed to examine the clinical tests under standardized conditions. Pain was induced by hypertonic saline injected into the proximal adductor longus (AL) tendon or rectus femoris (RF) tendon in 15 healthy male participants. Isotonic saline was injected contralaterally as a control. Pain intensity was assessed on a visual analog scale (VAS). Resisted hip adduction at three different angles and trunk flexion were completed before, during, and after injections. Pain provocation in the presence of experimental pain was recorded as a true positive compared with pain provocation in the non-pain conditions. Similar peak VAS scores were found after hypertonic saline injections into the AL and RF and both induced higher VAS scores than isotonic saline (P<0.01). Adduction at 0° had the greatest positive likelihood ratio (+LR=2.8, 95%CI: 1.09-7.32) with 45° (-LR=0.0, 95%CI: 0.00-1.90) and 90° (-LR=0.0, 95%CI: 0.00-0.94) having the lowest negative LR. This study indicates that the 0° hip adduction test resisted at the ankles optimizes the diagnostic procedure without compromising diagnostic capacity to identify experimental groin pain. Validation in clinical populations is warranted
APOPTOSIS RATE IN CUMULUS CELLS AS POSSIBLE MOLECULAR BIOMARKER FOR OOCYTE COMPETENCE.
Several lines of evidence showed that apoptosis rate of cumulus cells in oocytes derived by assisted
reproductive technologies could be used as an indicator of fertilizing gamete quality. Aim of the study
was to investigate the effects of three different ovarian stimulation protocols on the biological and clinical
outcome in hyporesponder patients. Collected data showed a higher significant rate of DNA fragmentation
index (DFI) in U group (patients treated with Highly Purified human Menopausal Gonadotrophin) than in
P group (treated with recombinant human Follicle Stimulating Hormone (r-hFSH) combined with
recombinant human Luteinizing Hormone (r-hLH)). Both groups R (treated with r-hFSH alone) and P
showed a significant increase in collected and fertilized oocytes number, embryo quality number. This
study showed that combined r-hFSH/r-hLH therapy could represent the best pharmacological strategy for
controlled ovarian stimulation and suggests to use DFI as a biomarker of ovarian function in
hyporesponder patients
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